(1) Field of the Invention
The present invention relates to an intake device for a V-type engine for synchronizing the carburetors of multiple cylinders of a V-type engine.
(2) Description of the Prior Art
In a typical V-type intake device for multi-cylinder engine for a motorcycle, each of the multiple cylinders has a separate carburetor, so there is the necessity of making synchronized control of the multiple carburetors. Japanese Utility Model Application Laid-Open Sho 60 No.61468 discloses an intake device in which the throttle shafts of the carburetors of the front and rear cylinders of a V-type engine are laid out coaxially on a line connected between the centers of the two carburetors (slightly inclined with respect to the line of center of the vehicle) and coupled to each other to thereby achieve synchronized control of multiple carburetors.
In an intake device configuration where the throttle shafts of multiple carburetors are merely connected as disclosed in Japanese Utility Model Application Laid-Open Sho 60 No.61468, there is a chance that the synchronization may be disordered if the carburetors are displaced relative to each other by vibrations and/or other reasons. To deal with this, as shown in FIG. 1, bodies 131 and 141 of carburetors 130 and 140 of the front and rear cylinders of a V-type engine may be connected to each other by means of linkage plates 150 and 150 so as to achieve an improved synchronized control of the two carburetors 130 and 140.
In this case, linkage plates 150 and 150 are arranged parallel to the vehicle's center line CL (perpendicular to the crankshaft) and attached to carburetors 130 and 140 by fasteners 159, 159, . . . , on both transverse sides of them. Since front and rear carburetors 130 and 140 are offset to opposite sides from each other, the attachment should be done with interposing spacers 158 and 158, . . . . Throttle shafts 136 and 146 of carburetors 130 and 140 are positioned perpendicular to the vehicle's center line CL and are coupled by a coupling linkage 160 which is parallel to linkage plates 150.
Thus, in the above intake device, the transversal distance between linkage plates 150 and 150 is large, increasing the weight and raising the cost. Further, since the transversal distance between linkage plates 150 and 150 is large, large overhangs of throttle shafts 136 and 146 (large projections of the shafts from bodies 131 and 141) need to be formed in order to couple throttle shafts 136 and 146 by means of coupling linkage 160. As a result, this configuration may cause increasing of the friction, being likely to be affected by dimensional errors and being low in its operativity.